The phrase "are generally much less" is correct and usable in written English.
It can be used to compare the degree or extent of something in a general context, often in discussions about differences in quality, quantity, or intensity.
Example: "These products are generally much less expensive than their competitors, making them a popular choice among consumers."
Alternatives: "are typically significantly lower" or "are usually considerably less".
Manmade materials are generally much less variable.
Party leadership races are generally much less interesting than pundits tend to hope.
Polls suggest that Americans are generally much less obsessed with immigration than are Britons.
The employees in a cafeteria deserve to get paid 21K because they didn't bother to go to college, have a less stressful lifestyle, took on less risk throughout their life and are generally much less educated".
From a literary perspective, his attempts to move away from his unique first-person mélange of fact and fiction into more traditional formats such as the essay or the play are generally much less satisfying.
About 1 in 400 male and 1 in 650 female live births demonstrate some form of sex chromosome abnormality, although the symptoms of these conditions are generally much less severe than are those associated with autosomal abnormalities.
It is taken as equal to evaporation from a large water surface and is generally much less than actual evapotranspiration.
Still, the actors took some coaxing here and there, not least because voiceover scale pay is generally much less than for a regular acting role.
Because none of the MAAC schools offered football scholarships, they were generally much less competitive than top-tier Football Championship Subdivision teams.
Service is generally much less jumpy and intrusive than it can be in these high-end places, though Fleur had issues.
While the impact of CCTV is generally much less than one would imagine given how widespread it has become, it is effective in some areas and is an aid to the police and private security.
